Hi Rtiny,
I think you will find that the 8.5's will stick out from the wheel arch and may require rolling of the lip or possibly fender flares.
Any particular reason for the 15" diameter? Check the link below, if they are still for sale, these are 16x8 at 0 offset.Were on a car without flares and any fouling, nearly got these myself but went a different direction.
http://www.viczcar.com/forum/topic/13649-watanabe-16x8-0-as-new-with-tyres-melbourne/page-2
Cheers, Hokin